1. Field
The invention relates to processes for extracting molybdenum values from aqueous solutions thereof, and in particular to selectively extracting molybdenum values from solutions which contain other dissolved metal values in addition to the molybdenum values.
2. State of the Art
Molybdenum values can be recovered from aqueous solutions thereof using organic solvent solutions of various amines and quaternary ammonium compounds to extract the molybdenum values from the aqueous phase.
In U.S. Pat. No. 3,449,066, a process is disclosed for extracting molybdenum values from aqueous solutions using a liquid organic medium containing alpha-hydroxy oxime as the extracting agent. As indicated in that patent, the extracted molybdenum values can be, at best, only partially stripped from the loaded organic phase with an aqueous ammonium hydroxide stripping solution. In U.S. Pat. Nos. 3,224,873; 3,440,036; and 3,455,680, it is taught that copper is also extracted from aqueous solutions by organic solutions containing alpha-hydroxy oxime, and U.S. Pat. No. 3,761,249 indicated that cobalt, nickel, and other metal values, if present, will also be extracted from the aqueous solution by such alpha-hydroxy oxime extracting solutions.
According to the teachings of U.S. Pat. No. 3,674,464, copper can be selectively extracted from aqueous solutions containing molybdenum and copper values by treating the aqueous solution with an organic solution containing alpha-hydroxy oxime at a pH above 5.7, preferable 6.9 to 9.6. It is further taught in U.S. Pat. No. 3,761,249, that copper values can be selectively extracted from solutions containing nickel and cobalt values in addition to the copper values by contracting the aqueous solution at a pH of between 6.5 and 8.5 with an organic extracting solution containing alpha-hydroxy oxime.
In U.S. Pat. No. 3,725,046, a process is disclosed for extraction of copper values from aqueous solutions thereof using an organic extractant solution containing 8 -hydroxy quinoline. It is taught that the presence of an alkylated phenol such as nonylphenol in the organic extraction promotes s substantial increase in efficiency of stripping copper values from the loaded organic phase using an aqueous, acidic solution as the stripping agent.